Project Summary/Abstract R01 CA129609A2 Over 50% of head and neck squamous cell carcinomas (HNSCC) recur despite multimodal therapy. As local treatment failures drive HNSCC morbidity and mortality, identification of effective treatments to prevent local recurrence has the potential to dramatically improve patient survival. One intervention strategy, which has proven effective in the management of both prostate and brain cancers, is the use of biodegradable polymer implants. While polymer implants provide a pharmacologic advantage, therapeutic benefits are highly dependent upon efficacy and possible synergism of the encapsulated agents. We propose to evaluate three derivatives of natural compounds: N-acetylcysteine (NAC), endostatin and a water-ethanol extract of freeze dried black raspberries, RO-ET. Studies in our laboratories have characterized some of the mechanisms by which NAC, endostatin and RO-ET suppress the HNSCC tumorigenic phenotype. NAC serves as a surrogate propeptide and inhibits activation and function of the basement membrane degrading gelatinase, MMP-9. Our data also show that the established angiostatic agent endostatin binds to HNSCC tropomysin microfilaments and inhibits HNSCC migration and invasion. RO-ET elicited a variety of chemopreventive effects in HNSCC cells that included reduction in VEGF release, inhibition of nitric oxide synthase, initiation of apoptosis and induction of differentiation. We hypothesize that the selected agents will reduce intracellular levels of reactive species, inhibit redox mediated gene expression and suppress pathways critical for HNSCC tumorigenesis. The research aims of this application are to: 1) determine effective agent dosing levels and evaluate agent combinations for synergistic or possible antagonistic effects (Aim 1.a.), 2) evaluate the effects of the chemopreventive agents on tumor-stromal interactions in HNSCC tumor explants (Aim 1.b.), 3) conduct pharmacokinetic analyses and determine therapeutic abilities to suppress HNSCC xenograft tumorigenesis (Aim 2).